26 



avoid a useless expenditure of labor, these larvae were not scattered 

 about indiscriminately, but were mostly placed in one heap consist- 

 ing of seven or eight layers reaching from the floor to the ceiling of 

 the nest, so that the same pieces of debris would serve for more than 

 one larva. One evening I placed a piece of boiled lean beef, about 

 I cm. square and half as thick, in the nest for food. By the next 

 morning it had been torn into shreds, and these had been used by 

 the ants in covering the larvae. If the larvae failed to attach their 

 threads the result was naked pupae. I saw one larva that had acci- 

 dentally wriggled out of its half-spun cocoon ; later it became a naked 

 pupa. When a cocoon was finished the workers removed it from 

 the pile, carefully cleaned off the bits of sponge, meat, etc., and 

 placed it with others in a clean pile. When the adult is ready 

 to emerge the workers remove the cocoon from the pile, bite it open, 

 and help out the young callow. The workers had placed thirty of 

 the larvae in one pile, and had fed them so heavily that they were 

 forming cjueen larvae. By March lo these were about twice the size 

 of the full-grown worker larvae. March 15, this nest showed the 

 most distinct grouping of the inhabitants of the nest I have ever 

 seen. There were seven distinct groups. These were ( i ) the thirty 

 queen larvae, (2) the buried larvae spinning cocoons, (3) a small 

 bunch of cocoons with the naked pupae (there were 15 naked pupae), 

 (4) all the rest of the cocoons (more than 100), (5) the nearly 

 full-grown larvae which were feeding heavily (these had their an- 

 terior ends pressed against a bit of egg, and with a lens one could 

 see their jaws working as they ate their food), (6) the youngest 

 larvae, but little larger than the egg, and (7) those larvae inter- 

 mediate in size between those of groups 5 and 6. On March 26 the 

 first three adults emerged and the next day seven more. This gives 

 a period of 24 and 25 days for these pupae. The empty cocoons 

 were carried over to one corner and placed in the waste heap. On 

 April I, one of the queen larvae was partly eaten, and from that time 

 these gradually disappeared, one or two a day, until May 5, when the 

 last two were eaten with the exception of one that had spun a cocoon 

 on April 19. During all this time I kept the colony well supplied 

 with food consisting of sugar-water, egg yolk, boiled beef, and in- 

 sect food such as white grubs, pieces of flies, beetles, etc. On May 

 5 the queen pupa was taken out of its cocoon, formed on April iq. 

 The following notes show something of the rate and time of deposi- 

 tion of chitin : — 



May 10. The queen pupa shows a deposit of chitin at the edge 

 of the mandibles, making a brownish line along the teeth. All the 



